sorry, i haven't read all your replies, and i only know Evans waterless coolant.
its no snake oil, it works. as far as i know it's used in smaller air planes since years.
advantages are: you don't need any pressure in the cooling system, it will stay clean, nothings like calcium to fall out, and last very long. why is the higher boiling point an advantage: because even if your temp gauge reads 90°C the temps close to the combustion chamber will be much higher. they can exceed the boiling point of water easily, forming a steam barrier, blocking heat from getting from the chambers to the liquid.
negative side: it's expensive, and some waterpumps don't like it and pump less volume than with waterbased stuff.
of cause it will not help with cooling systems that are blocked or undersized.
oh, and why are our engines running at temps that are lower that 100°C. because its impossible to control the temps with a waterbased coolant without much and expensive effort. and remember car makers like it cheap and easy
would i recommend it? no, if your satisfied with your currend coolant, stick with it.